In Graham's interview for the National Tattler, the interviewer sets the tape recorder down on the table next to Graham. In the next shot it is in the interviewer's hand and he sets it down a second time.
Obvious editing shows where Will Graham jumps through Dollarhyde's window in the climactic sequence: the pose that William Petersen is holding when he jumps at the window in slow motion is clearly not the same as that of his stunt double who actually falls through the window (following the cut between shots).
Towards the end of the movie, just as Dollarhyde is throwing Graham into the refrigerator, a person can be seen in the lower, left-hand corner. He is wearing a blue shirt. The victim is wearing a pink shirt and is later shown as still being on the table.
Close to the beginning of the movie as Will & Kevin are outside and Jack & Molly are sitting at the coffee table talking; there are figures seen moving in the reflection on the coffee table one of which is holding a video camera.
There is a discussion of Graham's Charter Arms Bulldog .44 being loaded with Glaser Safety Slugs for added lethality. Glaser Safety Slugs are designed to fragment on impact and release their loads of tiny shot pellets into the wound cavity, creating massive bleeding and near-certain death. When Graham shoots Dolarhyde, each round is shown to penetrate Dolarhyde's body, spattering blood on the wall behind him. Glaser Safety Slugs would not penetrate a body this way. An exit wound would be very unlikely.
The Chinese character carved in the tree (zhong1) doesn't mean "red dragon", it means "middle". The term "dragon tile" is a Western convention introduced by Joseph Park Babcock in his 1920 book introducing mahjong to America, and the zhong tile was originally related to archery: it indicated a hit on a target.
The movie implies that Will Graham uses a Charter Arms Bulldog .44 special pistol. If this were true, then Will could not shoot Francis Dollarhyde six times. A Charter Arms Bulldog only holds five rounds. Graham actually shoots the gun seven times, but two of the shots are repeated; the first and second shot that we see are actually the same one, as are the six and seventh. Thus, he only actually fires five bullets, which is the number that the gun can hold.
The pulse dialing telephones, such as the one given to Lecktor in his cell, had the ability to dial a number even without the rotary dial. All Lecktor needed to do is tap the digits of a telephone number on the switch hook to establish connection. While Lecktor in 'Manhunter' seems unaware of that fact, Lecter in 'Red Dragon' uses this method to dial the number he needs.
In the Atlanta hotel at the beginning, Will Graham is viewing the home movies in his hotel room. The TV set is a different size when there is an angle change. The first person shot is a multi frame rate monitor, and the shot from the back is a regular TV set.